GMDSS Flashcards
What are ALRS are there?
NP281 Maritime Radio Stations NP282 Radio Aids to Nav, DGPS, Legal Time, Radio Time Signals and e Pos Fox Systems NP283 MSI Services NP284 Met Obs Stations NP285 GMDSS NP286 Pilot services, VTS amd Port Ops
What is Sea Area 1?
Within 60 miles from a safe haven
Within VHF communication range with a shore station
What is Sea Area 2?
Up to 150 miles from shore
Excluding sea area 1
Within MF communication range
What is Sea Area 3?
Anywhere between 68 N or S
Excluding sea areas 1 and 2
HF and/or Sat C must be installed
What is Sea Area 4
Polar regions outside or area 3
HF equipment must be carried
Excluding areas 1 and 2
Under what circumstances can you use distress signals?
When there is grave and imminent danger
What are the various types of distress signal?
DSC Distress RT Mayday Fire on deck Gun fire Waving of arms November Charlie flags Pyrotechnics Etc etc
What action needs to be taken if a distress is received?
Obligations:
Not to terminate a distress transmission unduly
Provide assistance if possible/required
Relay the distress if appropriate
What vessels does the GMDSS code apply to?
All vessels over 500grt
Voluntary for vessels below this
What is the frequency of an EPIRB
406 MHz
Only 5 watt power requirement due to low earth orbit (LEO) of the corresponding satellites.
What is the alert pathway for an EPIRB?
EPIRB - LEO Satellite - Local User Terminal (LUT) - Mission Control Centre (MCC) - MRCC
What is the coverage and accuracy of the EPIRB system?
Global coverage is achieved with a fleet of satellites
Accuracy is approx 3 miles using SARSAT system
As accurate as GPS using GEOSAR system
What is the range of a radar-SART?
Radar transmissions are line of sights so:
approx 10 miles from a ship
approx 30/40 miles from an aircraft
What frequency activates a radar-SART?
9 MHz
X Band
3cm wavelength
What is the effect of sea state on a radar-SART?
Flat calm is not ideal as radar pulses can be reflected by the sea surface.
In rough conditions range will be greater on peaks and lesser in troughs.
How do you know any SART is being interrogated and what should you do when this happens?
Alarm will sound
Light characteristics will change
Call on Ch16 and fire flares
What is the SARTs batteries charge capable of?
96 hours in standby
Plus
8 hours of transmitting
What should you not do with a radar-SART?
Deploy alongside a radar reflector as this may obscure the SART.
What appears on the radar screen when a radar-SART has been interrogated?
12 dots, the closest of which is the position of the SART.
When within 1 mile, 12 arcs becoming concentric circles as it draws closer.
Radar range should be set to 6-12 miles to avoid target error.
What is the make up of an AIS-SART id number?
970
Follow by XX manufacturer code
Followed by XXXX serial number
This is nor a unique id.
What is the battery capacity of an AIS-SART?
Battery life is 96 hours of transmitting
What are the transmission characteristics of an AIS-SART?
8 messages within 14 seconds every minute.
4 messages on VHF 161.975
4 messages on VHF 162.025
How will a user know they have received an AIS-SART signal?
The following will be displayed on any equipment capable of receiving an AIS signal:
ID number UTC time Lat Long Range Bearing A cross enclosed by a circle
What will and AIS-SART no tell users?
It will not inform them if the signal has been detected as it has no receiver built in.
Monthly testing
SART live transmission and visual inspection. Battery exp date.
EPIRB test button and visual inspection. Exp dates for battery and HRU
What is the frequency of an EPIRBs low power homing signal?
121.5 MHz
What are the characteristics of the VHF antenna?
Either dipole or whip
Can full, half or quarter the wavelength of CH16
Full whip being a little less than 2 meters long
As high as possible as works by line of sight
Omnidirectional
DO NOT deform the natural shape in any way as this will reduce the functional area of the antenna
What are the characteristics of the MF/HF antenna?
Whip antenna between 7.5 and 9 meters
An antenna tuning unit is required to tune the whip over a variable frequency range
Can also be a wire antenna, commonly in a T or inverted L configuration
Omnidirectional
What are the characteristics of a fleet 77 antenna?
Large steerable parabolic antenna which produces a pencil beam which increases the signal strength
Dishes weighing around 27kg
The bean must be with 5deg of the satellite which in turn must be 5deg above the horizon (even in distress communications)
Can have blind arcs if placement is compromised
Power requirements are large due to tracking and the large bandwidth required to support speech (with the transmitter alone operating at 50-100W)
What are the characteristics of the satC antenna?
A small omnidirectional antenna
Weighing around 7kg
50W give a strong signal due to the narrow bandwidth
What is the range of a navtex station?
300-400 miles
What are the frequencies of navtex?
518 kHz in English
490 kHz in local language
Where can you find details of navtex stations?
ALRS/ADRS volumes 3 & 5
How many areas is the world divided into for navtex?
Which do you operate in mainly?
XXI area worldwide
IX Pakistan mainly
What are the navex message type which you can’t deselect?
A Navigation warnings
B Met warnings
D SAR and piracy
L* Nav warnings additional
What service is available through enhanced group calling (EHG)?
SafetyNET will provide met, SAR and nav warnings over the inmarsat system
